"It is impossible to count the blessings I have received over my years at Microsoft," Sinofsky said in a statement. "I am humbled by the professionalism and generosity of everyone I have had the good fortune to work with at this awesome company."

No reason has yet been given for his departure, and his intended future plans were not set out in Monday's (November 12) press release.

Sinofksy's responsibilities will be divided, as Julie Larson-Green is promoted to lead Windows software and hardware engineering.

Chief financial officer and chief marketing officer Tami Reller will take over responsibility for all business matters relating to Windows.

Both Larson-Green and Reller will report directly to Steve Ballmer, who thanked Sinofsky for his service.

"I am grateful for the many years of work that Steven has contributed to the company," said Microsoft CEO Ballmer. "The products and services we have delivered to the market in the past few months mark the launch of a new era at Microsoft."